Heartsease is a small settlement or hamlet in Powys, Wales. It is close to the border with England and lies near the junction of the two counties of Herefordshire and Shropshire. Historically, it was part of the ancient Cantref of Maelienydd in the Kingdom of Powys. For historical population figures see Powys History Project. The hamlet lies on the A4113 road between Knighton and Ludlow and is a few hundred metres from the River Teme (Welsh: Afon Tefeidiad). The settlement is the home of Radnor Hills, a business bottling local spring water.